Application Hangs when Scanning in Citrix XenApp

Thu, 06 Dec 2012 16:10:50 +0000

Another interesting issue today with an application that runs on Citrix XenApp.

Environment
Customer has a Citrix XenApp 5 environment running on Windows Server 2003. Clients are all Windows XP and run the Citrix Online Plugin 12.3 full screen.

RES Workspace Extender is used to integrate locally installed application into the XenApp Session. Users have no access to the local desktop.

Symptoms
This particular application scans invoices using a USB scanner attached to the client and runs them trough a workflow.
Whenever the Start scan button was pressed the application froze.

File not found error when scanning using Twain Redirection in Citrix XenApp

Tue, 04 Dec 2012 15:07:10 +0000

Scanners attached to client machines can be used from within a Citrix XenApp session via a mechanism called Twain Redirection.

For this mechanism to work correctly the file twain_32.dll must be present in the Windows directory.

On Windows 2008 this dll should be copied from winsxs (side by side) to the windows directory as described in CTX123981.

On Windows 2003 the dll is already in the correct directory, however applications that are not Terminal Server Aware cannot find this dll because the Windows directory is redirected to the user profile. Citrix recommends copying twain_32.dll to each user’s profile directory but this will take up unnecessary space.

So what alternatives do we have?

Twain on Remko's Blog

Application Hangs when Scanning in Citrix XenApp

File not found error when scanning using Twain Redirection in Citrix XenApp